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Author Topic: The Frankensilvia project. RB26 anyone ?  (Read 1239 times)

Offline BeamerKiller

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  • Location: Belgium
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The Frankensilvia project. RB26 anyone ?
« on: 05:29:33 AM / 17-Oct-14 »
Hey everybody !

Some of you may remember the beginning of my build about a year ago. The initial plan was to keep the build low cost and swap the original CA18ET for  a mightier CA18DET as I had that engine lying on my garage floor.

I start a whole new subject because the old subject here had its content deleted ?

Well, my fault I guess, I have been busy and did not have time to work on my car projects. Also my wife is pregnant with our first kid, so I had to make sure the whole heating system was built and finished at home before the baby arrives.

Anyways, let's talk about the Silvia :

This is the original car, never modified, never broken down, just rust here and there but nothing that can not be solved with a mig welder.




Bough it off one of my good friends for dirt cheap and i wanted to keep this car as just a fun street-legal go-kart.

So the inital plan was to use my S13's Ex-CA18DET (now my S13 is SR20 swapped, fatal error, i know) throw it in the S12, get that shit running and go spin the tyres at local drift events and so-on.

This is the CA18DET the day i brought it home with my station wagon :



I even bought a T28 turbocharger and tomei 264° camshafts to get a bit more power out of that engine .... but !
But the plans are going to change .

This summer I've been around auto meetings and met a lot of Nissan enthusiasts, one of them, who has become a good friend has an R33 Skyline GT-R which he had to replace the engine because for some unknown reason, it got short on oil and was damaged.

So while we were having a barbecue at my place (boy, you should have seen the street that day : a lot of S13's, two S12's (one of them was this one), the R33 GTR, a mazdaspeed miata and some vtec hondas) I ask this guy what he did with the old, damaged engine, and tells me like "nothing, it's just there lying on the floor"

So I went to his place, check that engine out and noticed that it could be repaired (needs a new crank and a bore expansion) so I just loaded it on the back of my little corolla hatchback, gave my friend a couple of hundred euros for it and drove home !

Here is the engine, sitting on an oil barrell il my garage :



And I got three boxes with a lot of spares too, including both stock turbos, but I suspect one of these two of being the responsible for the oil starvation, as it's got a lot of play.

A lot is missing though : the intake side, clutch, wiring, most of the sensors, plug cover and the crank pulley. As I'm going to rebuild the engine from scratch, I'll buy performance parts for replacing the missing ones, as I don't want to put used parts (except loom and sensors ...) on an engine that is gonna be entirely rebuilt.

So for the engine, I'm going this way :

- N1 Oil pump with Reimax gears
- N1 Crankshaft
- Tomei procam camshafts stage 3 for mid-revs
- Tomei high-revs valve springs and retainers with solid lifters
- Dual GT2540 turbo's
- Forged CP pistons
- Forged Manley conrods
- Power enterprise F1 tri-metal bearings
- Nismo 840cc injectors

And of course all the supporting mods (fuel, intake, big intercooler ....)

I am not pursuing big or massive power, as I don't think an S12 will ever be a dyno-breaker, plus, this car is gonna go outside and play (drift events, drift showoffs, hillclimb, time-attack and trackdays), so numbers don't matter, just fun matters !

I'd like to have 550-600hp but my target is to have a quick-spool and an engine full of power everywhere, not just at the end of the revving range ... I used to like turbo-lag on my S13 which had a very fat turbine mounted on the SR20DET. But RB26DETT is way different in its behavior, and putting a single large turbo would ruin it !

First off I had to deal with the body rust :

Before :



During the work :





I'm almost there, but now it's the small bits that I have to put together, and I don't have loads of free time, so I weld it slowly ;)

For the handling, I'm converting the front to S13 hubs, you find them dirt cheap around here (cost me 50 euros for both) :



So after that, it's easy, custom tension rods, S13 front coilovers and i'm done !

I also bought Z32 front brakes which are a direct bolt-on for S13 knuckles :



Rear end is gonna have a different treatment, as I don't wanna cut the frame to swap-in an S13 subframe, my bet is to keep the S12 Subframe and do some improvements :

I'll put Mercedes CLK front springs on the rear, because they are way harder and the lower the car a bit
As the subframe architecture does a good job keeping the whole thing very stiff, i'll just go with an OEM Subaru R180 diff which I can shim to lock harder and it will just need custom (reinforced) axleshafts and driveshaft to handle the "little" extra power from the RB ...

For the shock absorbers, Mercedes CLK ones will do (I still have to make some measurements, but they look like they fit) and if OEM fit, then aftermarket for mercedes fit too, the CLK has a lot of aftermarket support around here, plus it's cheap and good parts made in germany ^^

So the final product will look like something like this :

- RB26DETT fully forged, N1 Crank, N1 oil pump, dual GT2540 turbos
- RB25DET Gearbox
- S13 front knuckles with S13 coilovers S14 hubs and Z32 brakes
- R180 Re-shimmed differential
- Custom driveshaft and axleshafts
- Mercedes CLK front suspension on the rear
- Fully emptied interior with just a couple of fiberglass bucket seats and I'll just keep the dashboard, everything else has to go
- Exterior mods for the weight : I'll give it a try and mould the hood and fenders in fiberglass to save some weight on the front
- Exterior mods for the looks : I don't like showy or jazzy cars, I'll just put the SE bodykit and a set of nice wheels...

Only cut that will have to be made on the frame is for the gear lever hole as the RB gearbox is way bigger than the stock one.
I also want to mount the engine as far back as I can for weight distribution, of course i'll custom fabricate engine and tranny mounts

Target is to keep a playful car and not make a dragster out of a silvia, so 'ill try to compensate a bit the weight excess brought by the engine (about +100kg compared to the original CA18) by putting the battery in the trunk, fabricating hood and fenders out of fiberglass and shaving any unnecessary bracket in the engine bay.

Of course, rollcage and tower bars are planned

Hope you enjoyed this post and I'll try to update it as often as I can, cheers  :yay!:

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Understeer is when you hit the railguard with your front end
Oversteer is when you hit the railguard with your back end
Power is how hard you hit it
Torque is how far you push it away
Too much downforce and it chops your head off
Too less downforce and you fly away to hit the pine tree further down.